The present disclosure relates to toners suitable for electrophotographic apparatuses and processes for making such toners.
Toner blends containing crystalline or semi-crystalline polyester resins with an amorphous resin have been recently shown to provide very desirable ultra low melt fusing, which is important for both high-speed printing and lower fuser power consumption. These types of toners containing crystalline polyesters have been demonstrated suitable for both emulsion aggregation (EA) toners, and in conventional jetted toners. Combinations of amorphous and crystalline polyesters may provide toners with relatively low-melting point characteristics (sometimes referred to as low-melt, ultra low melt or ULM), which allows for more energy efficient and faster printing.
Fluorescent inks and dyes may be used as an authenticating feature in the document security industry. Secure documents, for example documents that are difficult to forge, may be conventionally created using inks that include fluorescent agents either alone or in combination with ordinary inks and/or pigments. Features printed using fluorescent inks are usually invisible under visible light, due to the colorless nature of the security inks or due to masking by other colorants in the document. Under proper illumination, however, the fluorescent features of the document are revealed in the form of a bright emission by the fluorescent dyes in the visible spectrum. For example, certain bank notes utilize visible features, such as holographic patches, microprinting and microtextures to conceal additional fluorescent threads and/or multi-colored emblems embedded in the bank note, which are only reveled under specific light frequencies. These features provide an increased level of security against counterfeiters by making the copying process of such a document more difficult.
Although fluorescent inks are available as described above, the use of toners for printing security features is somewhat limited. For example, U.S. Pat. No. 5,554,480, the disclosure of which is hereby incorporated by reference in its entirety, describes the use of ordinary organic fluorescent dyes which are applied via non-electrophotographic methods (flexo printing, inkjet, and the like). Furthermore, available fluorescent toners may appear colored under visible light, which defeats their usefulness as hidden security features.
Improved methods for producing toners which are suitable for use in creating security documents remain desirable.